The World Flora Online

Reduced leaves on the culm are referred to as sheaths; cataphylls are erect leaves at the base of the culms.

Analyses of DNA data show that Ecdeiocoleaceae is the closest living relative of the Poaceae (Briggs et al. 2000, Bremer 2002, Givnish et al. 2010), although analyses of some DNA data suggested that Ecdeiocoleaceae with Joinvilleaceae formed a clade sister to the Poaceae (Marchant & Briggs 2007). Features of Ecdeiocoleaceae have been used to assist the interpretation of Poaceae floral structures (Rudall et al. 2005). Culm anatomy (Cutler 1969, Briggs & Johnson 1998) shows many features (stomates confined to the base of deep grooves, enlarged epidermal cells overhanging the grooves and thick sclerenchyma caps on the ridges between the grooves) that are presumably xeromorphic adaptations to its seasonally arid climate. There is no sclerenchyma cylinder or parenchyma sheath, unlike Restionaceae.

Although the fruit is generally described as a small nut it is structurally an achene (Rudall et al. 2005).

Etymology: The family name is based on the type genus Ecdeiocolea, derived from the Greek ekdeia (= a falling short or laying bare) and coleos (= a sheath), referring to the absence of leaf sheaths on the stems.

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Culms unbranched, with 1–3 distal inflorescence branches (if only one branch (peduncle) this is continuous with the culm but more slender), terete, striate; leaves reduced to scarious sheaths; sheath overlapping at the base; inflorescence of one or few compact cylindrical or ovoid spikes terminating culm or inflorescence branches; spikes with zones of female and male flowers alternating once or twice along spike axis, the basal zones mostly female; flowers spirally arranged in 5 ranks, on very short pedicels.

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Herbs, monoecious, perennial, shortly or extensively rhizomatous, forming dense tussocks or extensive patches, rush-like, with sand-binding roots. Culms photosynthetic, unbranched with 1–3 distal inflorescence branches, terete, striate. Cataphylls well-developed, scarious. Leaves on the culm reduced to one (at the base of the peduncle) or few (3 or 4) scarious sheaths; sheaths open and overlapping at the base. Inflorescence of one or few compact cylindrical or ovoid spikes terminating culm or inflorescence branches. Spikes with zones of female and male flowers alternating once or twice along spike axis, the basal zones mostly female. Flowers spirally arranged in 5 ranks, on very short pedicels, subtended by a dark brown, rigid or scarious, ovate glume; glumes all or mostly subtending flowers. Perianth of 6 scarious to hyaline tepals in two whorls, dorsiventrally compressed, the outer two lateral segments folded and keeled, keel pubescent in male flowers. Male flowers with a minute pistillode and 4 or 6 stamens; filaments free, slender; anthers tetrasporangiate, dorsifixed, 2-lobed, latrorse, dehiscing by longitudinal slits. Female flowers with staminodes; ovary superior, free, 2- or 3-locular with 2 or 3 feathery, mostly stigmatic styles; each loculus with a solitary pendulous ovule. Fruit a capsule or a small nut (structurally an achene) shed with attached tepals and very short pedicel. Culm anatomy: with deep narrow grooves extending into the chlorenchyma, enlarged epidermal cells overhanging the grooves, thick sclerenchyma caps on the ridges between the grooves and with stomates and accompanying sclereids at the base or sides of the grooves; ridges with or without a central sclerenchyma rib.

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Germination hypogeal in Ecdeiocolea monostachya (Meney & Pate 1999: 21–22).

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Wind pollinated. Monoecious, with female and male flowers in alternating zones along the spike. The sequence of flowering of female and male zones at different times (Briggs & Tinker 2014) is an adaptation that would promote outbreeding. Flowering is synchronous in zones of male and female flowers, so that all spikes on a plant, often on many stems, are all female with conspicuous white stigmas or, at a different time, all male with yellow anthers. Rarely some male and female flowers on a plant flower at the same time. This synchronous flowering has been studied mostly in Ecdeiocolea monostachya but is general to the family, giving these wind-pollinated plants an out-crossing breeding system. The basal zone is female but often there are several female and male zones in the spikelet.

Recovery after fire is mainly by resprouting.

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Nutrient-poor sandy soils.

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An endemic Australian family of 2 genera and 3 species of nutrient-poor soils in southern Western Australia.

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n = c. 24 for Ecdeiocolea; c. 32 or 33 for Georgeantha (Briggs & Johnson 1998, Linder et al. 1998).

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APG IV (2016). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society 181: 1–20.

Bremer, K. (2002). Gondwanan evolution of the grass alliance of families (Poales). Evolution 56: 1374–1387. https://doi.org/10.1111/j.0014-3820.2002.tb01451

Briggs, B.G. & Johnson, L.A.S. (1998). Georgeantha hexandra, a new genus and species of Ecdeiocoleaceae (Poales) from Western Australia. Telopea 7(4): 307–312.

Briggs, B.G., Marchant, A.D., Gilmore, S. & Porter, C.L. (2000). A molecular phylogeny of Restionaceae and allies, in Wilson K.L. & Morrison D. (eds), Monocots – Systematics and Evolution, pp. 661–671. (CSIRO: Melbourne).

Briggs, B.G. & Tinker, A. (2014). Synchronised monoecy in Ecdeiocoleaceae (Poales) in Western Australia. Australian Journal of Botany 62(5): 391–402.

Clarke, I. (2015). Name Those Grasses – identifying grasses, sedges and rushes, p. 409, plate 34. (Royal Botanic Gardens Victoria: Melbourne.

Cutler, D.F. & Airy Shaw, H.K. (1965). Anarthriaceae and Ecdeiocoleaceae: two new monocotyledonous families, separated from Restionaceae. Kew Bulletin 19: 489–499.

Cutler, D.F. (1969). Ecdeiocoleaceae, in Anatomy of the Monocotyledons IV Juncales: 340–343. (Clarendon Press: Oxford).

Givnish, T.J., Ames, M., McNeal, J.R., McKain, M.R., Steele, P.R., dePamphilis, C.W., Graham, S.W., Pires, J.C., Stevenson, D.W.,  Zomlefer, W.B., Briggs, B.G., Duvall, M.R., Moore, M.J., Heaney, J.M., Soltis, D.E., Soltis, P.S., Thiele, K., Leebens-Mack, J.H. (2010). Assembling the tree of the monocotyledons: plastome sequence phylogeny and evolution of Poales. Annals of the Missouri Botanical Garden 97: 584–616. https://doi.org/10.3417/2010023

Ladd, P.G. (1977). Pollen morphology of some members of the Restionaceae and related families, with notes on the fossil record. Grana 16: 1–14.

Linder, H.P. (1992). The gynoecia of Australian Restionaceae: morphology, anatomy and systematic implications. Australian Systematic Botany 5(2): 227–245.

Linder, H.P., Briggs, B.G. & Johnson, L.A.S. (1998). Ecdeiocoleaceae, in Kubitzki, K. (ed.), The Families and Genera of Flowering Plants IV: 195–197. (Springer-Verlag: Berlin).

Mabberley, D.J. (2008). Mabberley’s Plant Book ed. 4: 319.

Marchant, A.D.& Briggs, B.G. (2007). Ecdeiocoleaceae and Joinvilleaceae, sisters of Poaceae (Poales): evidence from rbcL and matK data. Telopea 11(4): 437–450.

Meney, K.A. & Pate, J.S. (eds) (1999). Australian Rushes. Biology, Identification and Conservation of Restionaceae and Allied Families. (University of Western Australia Press: Nedlands).

Meney, K.A., Pate, J.S. & Hickman, E.J. (1999). Morphological and anatomical descriptions of Restionaceae and allied families and their distribution, in Meney, K.A. & Pate, J.S. (eds), Australian Rushes. Biology, Identification and Conservation of Restionaceae and Allied Families

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